For IBS (Irritable Bowel Syndrome), Specific Diets Are Less Important Than Expected

A large study from Chalmers University of Technology and Uppsala University in Sweden suggests that gluten and certain types of carbohydrates called “fodmaps” have a less than expected effect on IBS symptoms. No effect whatsoever for gluten could be seen and there was only a negligible effect of fodmaps. According to the Irritable Bowel Syndrome Scale (IBS-SSS), a change of more than 50 points indicates a clinically significant effect. The change between fodmaps and placebo was 42, and only 10 for gluten and placebo. Credit: Chalmers University of Technology | Elise Norden Win Strandqvist

Many IBS patients avoid certain types of food and often exclude gluten. However, a large new study of Chalmers University of Technology and Uppsala University, Sweden, do not show a relationship between high gluten intake and increased IBS symptoms. Researchers have found that a certain type of carbohydrate called “fodmaps” can exacerbate gut problems, however, the overall results suggest it has less effect than previously thought.

“IBS is a highly complex disease that involves many factors, but our results suggest that the effects of certain diets are not as significant as previously thought,” explains Elise Norden, PhD student in food sciences at Chalmers and lead author of the published scientific article. In the American Journal of Clinical Nutrition.

Irritable bowel syndrome (IBS) affects about three to five percent of the world’s population, and includes symptoms such as stomach pain, diarrhea and constipation. In the new study, which included 110 people with irritable bowel syndrome, researchers examined how people were affected by being served rice pudding prepared in different ways. One variety was high in gluten while the other contained large amounts of carbohydrates from the “FODMAPs” group — fermentable carbohydrates, including certain chains of fructose and lactose. Many foods are rich in food charts, including dairy products, types of bread, and some fruits and vegetables.
In addition to the specially prepared rice pudding, the researchers also provided a neutral dessert that acted as a placebo.

Double-blind knowledge of rice pudding

Study participants ate rice pudding rich in nutritional maps, gluten, and a placebo in random order for one week per category. The study was double-blind, meaning that neither the participants nor the researchers knew who ate which milk rice and when.

“Double-blind diet studies are difficult to do, where it can be clear to participants what they are eating. This is a huge hurdle, because knowing that something has been added or removed from the diet can affect the outcome. The fact that we succeeded,” says Elise Norden. In devising completely blind diets, along with the large number of participants, makes our study unique.”

Elise Norden

Elise Norden, PhD student, Department of Biology and Biotechnology, Chalmers University of Technology, Sweden. Credit: Chalmers University of Technology | Martina Butorak

The subjects’ digestive systems were stimulated by high doses (1.5 times the daily intake in the normal population) of fodmaps or gluten. FODMAPs worsened symptoms, but not to the extent that researchers had expected based on the results of previous studies. However, gluten was found to have no measurable negative effect on people’s perceived symptoms.

“Our results are significant and suggest that the psychological factor may be very important. IBS has previously been shown to be linked to mental health. Just the awareness that one is being tested in one of the studies is just the awareness that one is being tested in one of the studies,” says Per Hellstrom, the professor of gastroenterology at Uppsala University who took over medical responsibility for the study. It can reduce the burden of symptoms.

Distinguishing between the effect of gluten and fodmaps

In previous studies, researchers essentially excluded FODMAPs from people’s diets, and this showed a significant reduction in IBS symptoms. However, these studies had a small number of participants and were not conducted double-blind, which makes it difficult to evaluate the results objectively.

Richard Landberg

Ricard Landberg, Professor, Department of Food and Nutritional Sciences, Department of Biology and Biological Engineering, Chalmers University of Technology, Sweden. Credit: Chalmers University of Technology | Anna Lina Lundqvist

Many IBS patients exclude gluten from their diet, despite the lack of scientific evidence. Previous search results are inconsistent. Gluten-rich foods, such as bread, are often also high in FODMAPs — so one theory has been that it’s the nutritional maps in these foods, not gluten, that cause IBS symptoms. This illustrates the importance of studies to separate the effect of FODMAPs and gluten.

Study how the diet can be individually adapted

The new study is part of a larger project in which researchers are looking for biomarkers in the gut flora or blood so that they can predict health outcomes. The researchers want to investigate whether individuals can be divided into metabolic patterns — different groups based on how the individuals’ metabolism and gut flora respond to different diets, and whether these groups exhibit different symptoms of IBS.

“Finding objective biomarkers that can determine whether an individual belongs to a particular IBS metabolic pattern can make life easier for many individuals with IBS. Says Professor Richard Landberg, who leads the Department of Food and Nutritional Sciences at Chalmers University. For the technology, “there are many indications that it is possible to use objective labels for more individually tailored nutritional advice.”

The new IBS study also clearly shows significant individual variance when it comes to how different people are affected by a particular diet.

“Even if we see at the group level a moderate effect of mapping foods and no effect of stimulating gluten, some individuals may still react strongly to these foods as well. This is why it is important to consider individual differences,” says Elise Norden.

More on the study and fodmaps:

  • FODMAP is an acronym for “oligosaccharides, disharharides, monosaccharides, and fermentable polyols.” Examples of FODMAPs are the polymers of fructose, lactose, fructo/galacto-oligosaccharides, and glycoalcohols, which are found in a variety of foods, such as dairy products, grains, mushrooms, fruits, and vegetables. Products sweetened with xylitol, for example, are also rich in FODMAPs.
  • The scientific study, “FODMAPs, but not gluten, modest symptomatic irritable bowel syndrome: a triple-blind, double-blind, placebo-controlled, randomized trial” was published in the American Journal of Clinical Nutrition. The authors of the article are Elise Norden, Karl Brunius and Ricard Landberg of Chalmers University of Technology and Per M Hellstrom, Uppsala University.
  • In the study, subjects were given high doses (1.5 times the normal daily intake) of fodmaps (50 g) and gluten (17.3 g) and the results were compared with a placebo. Throughout the study, all subjects ate a diet with a minimum FODMAPs content and no gluten. Each trial period was 1 week, followed by a 1 week rest period. Blood and stool samples were provided weekly as subjects also completed questionnaires about their observed symptoms.
  • The study was funded by Formas and the Swedish Research Council.

Reference: “oligo-, di-, monosaccharides, and polyols (FODMAPs), but not gluten, elicit modest symptoms of irritable bowel syndrome: a randomized, double-blind, placebo-controlled, triple-randomized crossover trial” by Elise Nordin, Carl Brunius and Ricard Landberg Weber M Hellstrom, 7 Oct 2021, Available here. American Journal of Clinical Nutrition.
DOI: 10.1093/ajcn/nqab337

Leave a Comment